KR100907921B1 - Field emission device based on zinc oxide nanowire array - Google Patents

Abstract

The present invention relates to a field emission device based on zinc oxide nanowire array. Zinc oxide nanowires further comprising a conductor layer doped with aluminum (Al) for quality improvement based on the arrangement of zinc oxide (ZnO) nanowires produced by Metal Organic Chemical Vapor Deposition (MOCVD). An array-based field emission device is disclosed.

In the field emission device based on the zinc oxide nanowire array, a silicon substrate, a platinum thin film, a zinc oxide conductor layer doped with aluminum, a zinc oxide nanowire array layer, a ceramic ball spacer, and an indium tin oxide It provides a zinc oxide nanowire array based field emission device characterized in that the thin film and the glass layer are sequentially stacked.

Description

Field emission device based on zinc oxide nanowire array {ZnO NANOWIRE ARRAY FIELD EMISSION CELL}

The present invention relates to a zinc oxide nanowire array based field emission device, and more particularly to a zinc oxide nanowire array based field emission device including an aluminum (Al) doped conductor layer.

Recently, thin-walled flat panel displays such as liquid crystal displays (LCDs), plasma display panels (PDPs), and field emission displays (FEDs) have gained much attention because of their small footprint and excellent image reproducibility. Among these flat panel displays, the field emission display is very thin (about a few millimeters in thickness), has no curvature on the screen, and realizes display quality comparable to CRT with spontaneous fluorescence, and realizes and drives a wide viewing angle of 160 degrees or more in up, down, left, and right. It is attracting much attention as next generation information display because of many advantages such as low power consumption.

In the field emission device used in the field emission display, a field emission device is formed on a substrate on which a gate electrode is disposed and a cathode electrode is formed between a transparent front plate with an anode electrode and a back plate with a cathode electrode. As such, the field emission device used in the field emission display is also called an emitter.

When the field emission device applies a low voltage between the gate electrode and the cathode electrode, the field emission device emits electrons into the vacuum channel, and when the high voltage is applied to the anode electrode, the electrons emitted from the field emission device are accelerated by the anode voltage. The required information is displayed by hitting the phosphor applied to the anode electrode to emit light.

Since the field emission device is a core technology for emitting electrons, the processing technology and stability of the field emission device are important research and development goals.

One-dimensional nanostructures, such as carbon nanotubes (CNTs) and nanowires, have been sought for applicability to basic components of various nanoelectronic devices due to their unique physical and chemical properties. One field of application of one-dimensional nanostructures is field emission devices for next generation display devices. Research has focused on the application of CNTs with excellent electrical properties and inherent geometrical advantages (high aspect ratios) for field emission devices. However, zinc oxide nanowires, which are compound semiconductors having high aspect ratios, easy structure control and excellent stability due to structural instability and difficult synthesis of CNTs during high voltage discharge, have attracted attention.

Zinc oxide nanowires are semiconductors with a wide band spacing of about 3.37 eV and exciton binding energy of 60 meV, and can be applied to light emitting diodes, laser diodes, piezoelectric elements, and chemical sensors. In particular, it is possible to apply to the field emission device of the flat panel display of the vertically oriented zinc oxide nanowire in recent years.

Research on zinc oxide nanowires having various applications requires practical application of zinc oxide nanowires with desired shapes, sizes, and lengths. Recently, research has been conducted on the method of growing and arranging zinc oxide nanowires through various pre-treatments of substrates and synthesizing nanowires having high crystallinity and optical properties in order to have better field emission characteristics. . In addition, some studies on the role of surface adsorption species, which are important factors influencing the field emission, have been conducted.

The vertical orientation of the zinc oxide nanowires is possible with the use of substrates with similar crystallographic properties to zinc oxide, but all of these materials are insulators. On the other hand, the use of a doped silicon or metal thin film deposited substrate for maintaining the current path has a negative effect on the vertical orientation of the zinc oxide nanowires. Therefore, the known zinc oxide nanowire field emission devices do not solve the conflicting technical problem.

In the construction of a field emission device based on zinc oxide nanowires according to the prior art, a conventional zinc oxide nanowire field emission device structure has a substrate on which a doped silicon or metal thin film is deposited to provide an electrically conductive path in a nanowire arrangement. Apply. However, in the prior art, the vertical alignment of the zinc oxide nanowires is difficult.

SUMMARY OF THE INVENTION An object of the present invention is to provide a zinc oxide nanowire array-based field emission device that improves the structure of a zinc oxide nanowire field emission device by applying a conductor layer doped with aluminum.

Another object of the present invention is to provide a zinc oxide nanowire array-based field emission device, characterized in that the conductor layer doped with aluminum maintains a current transfer path.

Accordingly, the present invention provides a silicon oxide nanowire array-based field emission device comprising: a silicon substrate, a platinum thin film, a zinc oxide conductor layer doped with aluminum, a zinc oxide nanowire array layer, a ceramic ball spacer, and an oxide It provides a zinc oxide nanowire array-based field emission device characterized in that the indium tin thin film and the glass layer are sequentially stacked, thereby improving the vertical orientation of the zinc oxide nanowires, and provides a smooth current conduction path between the electrode layer and the nanowires. do.

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The zinc oxide nanowire array-based field emission device of the present invention formed as described above not only has excellent vertical orientation of the zinc oxide nanowires on the substrate, There is an advantage that the array synthesis is easy.

Further, in the present invention, it is very densely distributed in a uniform size on the aluminum-doped zinc oxide thin film, and thus can be easily used in the field emission device having excellent electrical and optical properties.

In addition, in the present invention, the electrical contact is improved by maintaining the crystallinity and current transfer path of the zinc oxide nanowire field emission device, so that the zinc oxide nanowire field emission display device may be easily used.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a perspective view of a zinc oxide nanowire array based field emission device including a conductor layer doped with aluminum. The zinc oxide nanowire-based field emission device structure includes a silicon (Si) substrate 10, a platinum (Pt) thin film 20, a conductor layer 30 doped with aluminum (Al), and zinc oxide (ZnO) The route arrangement layer 40, the ceramic ball spacer 50, the indium tin oxide (ITO) thin film 60, and the glass layer 70 are sequentially stacked.

Of the zinc oxide nanowire-based field emission device structure The platinum (Pt) thin film 10, the aluminum-doped conductor layer 30, and the zinc oxide nanowire array layer 40 are the cathode, the indium tin oxide thin film 60 is the anode, and the ceramic ball spacer 50 serves to finely maintain the gap between the cathode and the anode for field emission from the nanowire emitter. The platinum (Pt) thin film 10 is configured to transmit current to the zinc oxide nanowire array layer 40, and indium tin oxide (ITO) is used as a transparent electrode.

The zinc oxide nanowire array layer 40 is manufactured by metal organic chemical vapor deposition (MOCVD), and the manufacturing process of the zinc oxide nanowire array based field emission device is performed in vacuum to obtain zinc oxide To enable field emission from route emitters.

The conductor layer of the aluminum (Al) -doped conductor layer 30 includes zinc oxide, and may be referred to as a transparent conductive zinc oxide relaxation layer doped with aluminum, and may include a zinc oxide nanowire array layer 40 and a platinum thin film ( 20) is formed between. The zinc oxide thin film 30 doped with aluminum (Al) has the characteristics of a dual purpose layer having an electrode and a nanowire orientation, and has a basic performance requirement as a conductive layer because its electrical conductivity is measured as 6 × 10 ⁻³ μm.

FIG. 2 is a scanning electron microscope (SEM) photograph of zinc oxide nanowires synthesized on an aluminum-doped conductor layer. Zinc oxide nanowires synthesized by a non-catalytic organometallic chemical vapor deposition method are shown on the aluminum oxide doped zinc oxide thin film 30. The length and diameter of the zinc oxide nanowires are approximately 1.6 μm and 40 nm, corresponding to an aspect ratio of 40.

Zinc oxide nanowires at magnification magnified on the right side of FIG. 2 can be seen that the zinc oxide nanowires are well oriented perpendicular to the substrate. It can be seen that the zinc oxide nanowires shown on the right have better vertical orientation than the zinc oxide nanowires synthesized on the conventional silicon substrate or metal substrate shown on the left.

Figure 3 shows the X-ray diffraction spectrum of the zinc oxide nanowires synthesized on the aluminum-doped conductor layer. The vertical alignment of the zinc oxide nanowires shown in FIG. 2 can be verified through x-ray diffraction spectra for the nanowire array layer shown in FIG. 3.

Since the surface index of zinc oxide shown in the graph is smaller, the interplanar distance increases, so that the diffraction peak occurring at the plane corresponding to the lowest surface index is shown at the lowest 2θ among the diffraction peaks. The zinc oxide nanowires tend to grow in the [0001] direction, and the diffraction peak intensities of FIG. 3 shown on a logarithmic scale are observed to the maximum in the (0002) plane, indicating that the crystallinity is excellent. The other (10-11) plane peaks showed a contrast of less than 1% of the intensity of the (0002) plane peaks, indicating that the zinc oxide nanowires were well aligned in the [0001] direction. These results show that the zinc oxide nanowires have excellent optical properties.

In addition, the interfacial distance of the (0002) plane of the zinc oxide nanowire calculated by analyzing the X-ray diffraction spectrum was 5.207 5., which is 0.096% difference from the value of 5.202 기준 of the reference interplanar distance. It can be seen that it also contributes to resolving the residual stress of the zinc oxide nanowires.

4 is a graph showing field emission current density change according to an applied voltage of zinc oxide nanowires according to the present invention. In more detail, the correlation between the applied electric field and the emission current density showing the operating characteristics of the device structure shown in FIG.

In general, the field emission phenomenon occurs when the electric field strength is 5 x 10 ⁷ V / cm or more. However, when the strength of the electric field is more than 5 x 10 ⁵ V / cm, dielectric breakdown occurs between the flat metal electrodes. Therefore, in the case of metal, the cathode should be manufactured in the form of a pointed tip in order to easily cause field emission. The work function of the material of the device also has a great influence on the field emission, and generally has a low work function to make the field emission easily occur.

It can be seen from FIG. 4 that the on-voltage of the structure of the field emission device based on the zinc oxide nanowire array is clearly defined as 5 V / μm, and the electric current-current density change follows an exponential relationship, so the measured current is Fowler-Nordheim. (Folwer-Nordheim) It can be confirmed that this is due to the field emission complying with the tunneling. That is, it can be seen from the graph of FIG. 4 that the aluminum oxide-doped zinc oxide thin film 30 operates normally as a conductive layer.

Since the zinc oxide nanowires formed according to the present invention are oxides, they are not only excellent in mechanical and thermal stability, but also grown by organometallic chemical vapor deposition without a metal catalyst, and thus have fewer defects, excellent crystallinity, and large area. Even on the substrate, the length, thickness and density distribution are grown to be uniformly well oriented in the vertical direction.

In the field emission device based on the zinc oxide nanowire array formed as described above, a zinc oxide nanowire substrate is formed by applying a zinc oxide thin film 30 doped with aluminum as a dual target layer of an electrode and a nanowire orientation when the field emission device is configured. A new field emission device structure can be implemented that is well oriented perpendicular to the surface and provides an electrically conductive path to the zinc oxide nanowire alignment layer 40.

In addition, doping aluminum in the zinc oxide thin film enables the implementation of electrical conductivity at the level of indium tin oxide, which is currently applied as a transparent electrode for display. Since the crystallographic characteristics of the zinc oxide thin film are the same as those of the zinc oxide nanowire, the vertical alignment and the non-alignment of the nanowire are achieved. It is also possible to implement a defect electrode and a zinc oxide nanowire interface, thereby preventing deterioration of device operation characteristics due to contact resistance and potential difference at the interface.

Therefore, the requirement that the zinc oxide nanowires have excellent vertical alignment on the surface of the field emission device substrate while providing an appropriate current transfer path as the zinc oxide nanowire field emission device is solved. Will contribute to practical use.

The scope of the present invention is not limited by the above embodiments and drawings, and the scope of the present invention will be limited only by the contents described in the claims below.

1 is a schematic diagram of a zinc oxide nanowire array based field emission device comprising a conductor layer doped with aluminum.

2 is a scanning electron microscope (SEM) photograph of zinc oxide nanowires synthesized on an aluminum-doped conductor layer.

3 is an X-ray diffraction spectrum of zinc oxide nanowires synthesized on an aluminum doped conductor layer.

Figure 4 is a graph of the field emission current density change according to the applied voltage of the zinc oxide nanowires according to the present invention.

Claims (4)

In a zinc oxide nanowire array-based field emission device, Oxide characterized in that a silicon substrate, a platinum thin film, a zinc oxide conductor layer doped with aluminum, a zinc oxide nanowire array layer, a ceramic ball spacer, an indium tin oxide thin film, and a glass layer are sequentially stacked Field emission device based on zinc nanowire array. delete delete delete

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